Precious metal alloy electrocatalyst with small size and high loading capacity

Abstract

The invention relates to a noble metal alloy electrocatalyst with small size and high loading capacity. The catalyst comprises an in-situ carbon carrier and small-size noble metal alloy nanoparticles loaded on the carrier, the loading capacity is 50wt%-90wt%; the precious metal alloy comprises an alloy composed of a precious metal and at least one different transition metal M, and the average particle size of the precious metal alloy nanoparticles is 1-10 nm; in the preparation method, the particle size growth under high-temperature annealing is limited by applying pressure, so that homogenization, pressure assistance and high-temperature annealing work together, and the noble metal alloy nanoparticle assembly catalyst which is anchored by carbon and has two-dimensional characteristics is prepared. The method is used for solving the problem that the size of catalyst particles becomes large in the alloying process, high metal loading capacity is achieved, and the activity and stability of the catalyst are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to the synthesis of electrocatalysts and chemical synthesis. Specifically, a noble metal alloy electrocatalyst with small size and high loading and a preparation method thereof are proposed. Background Art

[0002] Fuel cells are one of the key technologies to replace the existing fossil fuel energy systems. In particular, proton exchange membrane fuel cells have been widely studied as power sources in fuel cell vehicles. Due to the scarcity of platinum, there is a need to find a highly active and low-cost cathode electrocatalyst to promote the commercialization of fuel cell vehicles.

[0003] Introducing transition metals into Pt to form alloyed nanoparticle catalysts is a simple method, which has been widely studied due to its enhanced electrocatalytic activity and reduced Pt loading. However, the alloys synthesized at low temperatures usually have a low degree of alloying and large particle sizes at high temperatures, which makes the alloy catalysts prone to dissolution and loss of transition metals in actual environmental applications. The large size results in the exposure of low active sites, leading to lower durability and stability of the catalysts.

[0004] Many researchers are also committed to synthesizing noble metal-based alloy catalysts for fuel cell applications. However, traditional alloy catalysts are usually nanoparticle catalysts loaded on carbon at high temperatures, resulting in particle agglomeration and growth, and the highest loading of the catalysts does not exceed 40%. This leads to lower effective catalytic performance of the catalysts in applications. While it is difficult to increase the loading, there are also problems such as noble metal particle agglomeration and uneven particle distribution. Moreover, the structure of the monodisperse metal nanoparticle catalysts loaded on carbon at high temperatures has serious drawbacks, prone to nanoparticle agglomeration and shedding, and having a lower electrochemically active surface area and higher mass transfer resistance.

[0005] In the prior art, in CN201910617257.4, "A Catalyst of Noble Metal Nanoparticles Supported on Carbon Nanosheets, Its Preparation Method and Application", using inorganic salts as templates and providing commercial carbon sources, noble metal nanoparticle catalysts are supported on commercial carbon precursors. The obtained catalysts are in the form of sheets, with the size of noble metal nanoparticles ranging from 2 nm to 50 nm and the content of noble metals ranging from 0.5 wt% to 10 wt%. However, it still has problems such as uneven particle size and low noble metal loading, which limits the further improvement of catalyst activity and stability. In CN202210845558.4, "A Pt-Based Intermetallic Ordered Alloy, Preparation Method and Application", a layer of heteroatom-rich coating layer is constructed on the carrier, and then disordered alloy particles or mixed Pt alloy precursors are loaded and pyrolyzed at high temperature, which can effectively prevent the further aggregation of Pt particles. Although small-sized and highly dispersed PtM intermetallic ordered alloy particles can be obtained, significantly reducing the pyrolysis time and temperature of the alloy catalyst, there are still problems such as relatively complex processes, low Pt loading (27.7 wt%), and low Pt utilization rate. Xun Hong et al. in Angew. Chem. 2021, 133, 6607–6612 used inorganic salts as templates and platinum acetylacetonate as metal precursors, without using specific commercial carbon sources, and synthesized pure platinum catalysts deposited on carbon carriers through the direct pyrolysis of acetylacetonate salts, preparing catalysts with excellent structural characteristics and excellent performance. However, due to the high cost of pure platinum catalysts, there is still a large room for improvement in their activity and stability.

[0006] Therefore, designing a noble metal-based alloy nanoparticle catalyst with small size, high loading, high activity, and high stability remains a huge challenge. Summary of the Invention

[0007] The object of the present invention is to provide a noble metal alloy electrocatalyst with small size and high loading and its preparation method in view of the deficiencies of the prior art. The electrocatalyst includes an in-situ carbon carrier and small-sized noble metal alloy nanoparticles supported on the carrier; the metal loading is 50 wt% to 90 wt%; in the preparation, by further improving the preparation method combining pressure-assisted regulation and traditional high-temperature annealing, under the condition of alloying nanoparticles at traditional high temperature, pressure is added to limit the growth of particle size under high-temperature annealing and make the particles uniform, so that pressure assistance and high-temperature annealing work together, thereby preparing a catalyst assembled body of noble metal alloy nanoparticles with two-dimensional characteristics anchored by carbon. The present invention is used to solve the problem of the increase in particle size during the high-temperature alloying process of catalyst particles, and achieve a high metal loading, effectively improving the activity and stability of the catalyst.

[0008] The technical solution of the present invention is as follows:

[0009] A small-sized, high-loading noble metal alloy electrocatalyst, which comprises an in-situ carbon support and small-sized noble metal alloy nanoparticles supported on the support; the loading is 50wt% - 90wt%; the average particle size of the noble metal alloy nanoparticles is 1 - 10nm;

[0010] The noble metal alloy comprises an alloy composed of one noble metal and at least one different transition metal M;

[0011] Wherein, the noble metal is one of platinum, palladium, iridium, rhodium, ruthenium, and the transition metal M is at least one of iron, cobalt, nickel, copper, manganese, zinc, gallium, platinum, palladium, iridium, rhodium, ruthenium;

[0012] The noble metal alloy is at least a binary noble metal alloy, and the at least binary noble metal alloy can be understood as a binary, ternary, quaternary, quinary, or even multi-component noble metal alloy.

[0013] A preparation method of the small-sized, high-loading noble metal alloy electrocatalyst, which comprises the following steps:

[0014] Step 1, adding an organic noble metal salt precursor, a transition metal M metal salt precursor, and a template salt into a mixed solvent for mixing, ultrasonically stirring for 20 - 40 minutes, drying and grinding, and obtaining a powder sample for standby;

[0015] Wherein, the mixed solvent composition is anhydrous ethanol / deionized water; 0.01mmol - 0.05mmol of the organic noble metal salt precursor, 0.01mmol - 0.05mmol of the transition metal M metal salt precursor, and 50mg - 1000mg of the template salt are added to every 10mL of the mixed solvent; the mass ratio of the organic noble metal salt precursor to the template salt is 1:5 - 1:100; the molar ratio of the organic noble metal salt precursor to the transition metal M metal salt precursor is 10:1 - 1:10;

[0016] Step 2, transferring the above powder sample to a high-pressure furnace, heating to 500°C - 1500°C, annealing in an inert atmosphere for 0.5h - 48h, after cooling to room temperature, washing several times with an anhydrous ethanol / deionized water mixed solution, centrifuging to collect the black product, and drying to obtain the different types of small-sized, high-loading noble metal-based alloy catalysts;

[0017] The pressure of the inert atmosphere is 0.1MPa - 50MPa higher than the standard atmospheric pressure.

[0018] The organic noble metal salt precursor is platinum acetylacetonate, palladium acetylacetonate, iridium acetylacetonate, rhodium acetylacetonate, or ruthenium acetylacetonate.

[0019] The transition metal M metal salt precursor is at least one of iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate, manganese acetylacetonate, zinc acetylacetonate, gallium acetylacetonate, platinum acetylacetonate, palladium acetylacetonate, iridium acetylacetonate, rhodium acetylacetonate, ruthenium acetylacetonate.

[0020] The template salt is one of potassium chloride, potassium bromide, sodium chloride, sodium bromide, sodium carbonate, sodium acetate, and preferably potassium chloride.

[0021] The volume ratio of anhydrous ethanol / deionized water in the mixed solvent is 1:1.

[0022] In step one, the method for drying the mixed solution is rotary evaporation solvent drying method or forced air oven drying method. After drying, the solid powder is ground thoroughly for 5 - 10 minutes. The purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form the assembly.

[0023] The heat treatment annealing temperature is preferably 600°C - 800°C. The pressure of the heat treatment inert atmosphere is preferably 0.1 MPa - 10 MPa higher than the standard atmospheric pressure. The atmosphere condition is preferably one of argon and nitrogen. The purpose is to make the metal particles more uniformly dispersed during calcination. The heating rate is 1°C / min - 50°C / min, and the holding time is 1 h - 24 h.

[0024] In the above step two, the volume ratio of anhydrous ethanol / deionized water in the cleaning solution is 3:1 - 1:3, and the number of cleaning times is 1 - 5 times.

[0025] The application of the catalyst can be used in, but not limited to, proton exchange membrane fuel cells as the electrocatalyst of the membrane electrode. Since it is an assembly of small - sized, high - loading noble metal - based alloy nanoparticles, it can be used to solve the problems of complex processes, catalyst costs, and activity and durability during practical applications in the preparation of small - sized noble metal - based alloy catalysts.

[0026] The substantial features of the present invention are:

[0027] The provided noble metal alloy electrocatalyst of the present invention has a small particle size distribution, and at the same time, the in-situ carbon-anchored catalyst nanoparticle assembly has two-dimensional characteristics and enables the catalyst to have a high metal loading. The preparation method of this catalyst mainly uses inorganic salts as templates, and organic noble metal salts and transition metal salt M as precursors. After thermal decomposition and reduction, an in-situ carbon-anchored noble metal-M-based alloy nanoparticle two-dimensional assembly is initially obtained; then this alloy nanoparticle is subjected to high-temperature calcination treatment in an inert atmosphere under pressure for a certain period of time to achieve the preparation of a high-loading, ultra-small noble metal alloy. This preparation method has a simple process, good universality, and due to the existence of pressure, it can effectively inhibit the sintering and growth during the high-temperature alloying process of noble metal-M nanoparticles, realizing the preparation of noble metal-M-based alloys with a size less than 10 nm; due to the existence of template salts, noble metal-M-based alloy nanoparticles can be assembled, significantly improving the exposure of active sites, enhancing the interaction between particles, and alloyed nanoparticles can weaken problems such as the loss of transition metals, which has important scientific and engineering significance in improving the stability of the catalyst.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) By adopting a pressure-assisted synthesis method, combining pressure with high-temperature thermal annealing, under the action of pressure, while ensuring that high-temperature annealing alloyizes the noble metal-M, the size of nanoparticles is restricted, making the nanoparticles more uniform. Applying appropriate pressure and high temperature to synthesize small-sized noble metal alloy catalysts, this method has the advantages of simple preparation process, good universality, no complex pretreatment process, and no addition of other chemical substances;

[0030] (2) Using the organic matter in the annealed metal salt precursor as a carbon carrier to in-situ anchor alloy nanoparticles, enabling the synthesized catalyst to have a very high metal loading, greatly improving the utilization rate of noble metals, and enabling the catalyst to have higher effective catalytic performance in applications. Taking the PtNi alloy catalyst as an example, the mass activity is as high as 0.42 Amg Pt -1 , which is 2.5 times that of commercial Pt / C catalysts;

[0031] (3) Under the action of template salts, small-sized noble metal-M-based alloy nanoparticle assemblies with two-dimensional characteristics are synthesized, thus greatly improving the exposure of active sites. Together with carbon anchoring, it can effectively limit particle agglomeration. From these three aspects, the overall stability of the catalyst can be improved. Taking the PtNi alloy catalyst as an example, after 10,000 cycles of accelerated degradation testing, the half-wave potential of the catalyst only has a loss of 6 mV, while the half-wave potential of commercial Pt / C catalysts has a loss of 30.6 mV. Description of the Drawings

[0032] Figure 1 It is a low-magnification transmission electron microscopy image of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0033] Figure 2 It is a high-magnification transmission electron microscopy image of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0034] Figure 3 It is a particle size statistical chart of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0035] Figure 4 It is an HRTEM image of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0036] Figure 5 It is an XRD pattern of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0037] Figure 6 It is a thermogravimetric analysis chart of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0038] Figure 7 It is the corresponding elemental surface scan image of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1;

[0039] Figure 8 It is the polarization curve of the small-sized and high-loading PtNi alloy catalyst obtained in Example 1 and commercial Pt / C;

[0040] Figure 9 It is a low-magnification transmission electron microscopy image of the small-sized and high-loading PtCo alloy catalyst obtained in Example 2;

[0041] Figure 10 It is an XRD pattern of the small-sized and high-loading PtCo alloy catalyst obtained in Example 2;

[0042] Figure 11 It is a low-magnification transmission electron microscopy image of the small-sized and high-loading PtFe alloy catalyst obtained in Example 3;

[0043] Figure 12 It is an XRD pattern of the small-sized and high-loading PtFe alloy catalyst obtained in Example 3;

[0044] Figure 13 It is the transmission electron microscopy image of the small-sized and high-loading Pt 3 Ru 2 alloy catalyst obtained in Example 4;

[0045] Figure 14It is the small-sized and high-loading Pt obtained in Example 4 3 Ru 2 Particle size statistical chart of the alloy catalyst;

[0046] Figure 15 It is the small-sized and high-loading Pt obtained in Example 4 3 Ru 2 Corresponding XRD pattern of the alloy catalyst;

[0047] Figure 16 It is the small-sized and high-loading Pt obtained in Example 4 3 Ru 2 Elemental surface scan pattern of the alloy catalyst;

[0048] Figure 17 It is the transmission electron microscopy image of the small-sized and high-loading RuCo alloy catalyst obtained in Example 5;

[0049] Figure 18 It is the transmission electron microscopy image of the small-sized and high-loading PtZn alloy catalyst obtained in Example 6;

[0050] Figure 19 XRD pattern of the small-sized and high-loading PtZn alloy catalyst obtained in Example 6;

[0051] Figure 20 It is the small-sized and high-loading PtGa obtained in Example 7 2 Alloy catalyst transmission electron microscopy image;

[0052] Figure 21 It is the small-sized and high-loading PtGa obtained in Example 7 2 XRD pattern of the alloy catalyst. Detailed implementation manners

[0053] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and should not be construed as limiting the present invention.

[0054] First, the present invention provides a small-sized and high-loading noble metal alloy catalyst, which includes an in-situ carbon carrier and a small-sized and high-loading noble metal alloy catalyst anchored on the carbon carrier. The noble metal alloy contains one noble metal and at least one different transition metal M. The average particle size of the noble metal alloy nanoparticles is not greater than 10 nm, and the metal loading is between 50% and 90%.

[0055] The in-situ carbon support specifically refers to that when the metal element in the organometallic precursor is reduced, the organic matter in the organometallic precursor is reduced to a carbon substrate through high-temperature and high-pressure treatment, so that the metal element is in-situ reduced and anchored on the carbon substrate, serving as the in-situ carbon support.

[0056] Among them, the noble metal is one of platinum, palladium, iridium, rhodium, and ruthenium, the transition metal M is at least one of iron, cobalt, nickel, copper, manganese, zinc, gallium, platinum, palladium, iridium, rhodium, and ruthenium, and the noble metal alloy is at least a binary noble metal alloy. The at least binary noble metal alloy can be understood as a binary, ternary, quaternary, quinary, or even multi-component noble metal alloy.

[0057] Specifically, taking the noble metal as Pt and the transition metal M as Ni element as an example, Figure 1 shows the low-magnification transmission morphology image of the small-size and high-loading PtNi alloy catalyst prepared by the present invention. As can be seen from Figure 1 , the PtNi nanoparticles are uniformly distributed and assembled on the surface of the carbon support, showing two-dimensional characteristics without segregation or agglomeration; Figure 2 is its high-magnification transmission morphology image. As can be seen from Figure 2 , the PtNi alloy catalyst has a relatively high metal loading; and a particle size statistical chart as shown in Figure 3 can be obtained, with PtNi nanoparticles having an average particle size of 3.2 nm; Figure 4 is its high-resolution transmission image, from which the lattice fringes of the ordered alloy of PtNi nanoparticles can be seen; similarly, through the XRD pattern shown in Figure 5 , it can be obtained that the synthesized Pt-Ni alloy has a relatively high degree of alloying, and the ordered crystal structure of the PtNi nanoparticles can be seen.

[0058] On the other hand, the present invention further provides a preparation method for the above-mentioned small-sized, high-loaded precious metal alloy electrocatalyst, taking PtNi alloy as an example, comprising the following steps: step 1, dissolving a Pt metal salt precursor, a transition metal Ni metal salt precursor and a template salt KCl in a mixed solvent of anhydrous ethanol / deionized water and mixing them evenly, stirring them ultrasonically for 20 to 40 minutes to completely dissolve them, and obtaining a mixed solution of the metal salt precursor and the template salt, and drying and fully grinding the mixed solution by rotary evaporation, in order to uniformly coat the metal salt precursor on the template salt; step 2, The fully ground powder sample is transferred to a high-pressure furnace for uniform annealing, and alloying and annealing are performed under inert atmosphere conditions of specific temperature and pressure (wherein, the purpose of the nanoparticles being treated with inert gas is to serve as a protective atmosphere to allow the nanoparticles to grow uniformly, and annealing is performed under high temperature and high pressure. Under the condition of traditional high temperature to order the particles, pressure is added to limit the growth of the particle size under high temperature annealing and to make it uniform). After cooling to room temperature, the powder sample is washed several times with a mixed solution of anhydrous ethanol / deionized water, and the black product is collected by centrifugation. After drying, the small-sized, high-loaded PtNi alloy catalyst is obtained.

[0059] Example 1

[0060] A preparation method of a small-sized, high-load PtNi alloy electrocatalyst comprises the following steps:

[0061] (1) 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (6.6 mg) of nickel acetylacetonate and 400.0 mg of potassium chloride were mixed, 5 ml of anhydrous ethanol and 5 ml of deionized water were added to dissolve the mixture, ultrasonicated for 30 min, and after sufficient mixing and dissolution, the liquid was dried using a rotary evaporator. The solid sample was then scraped off the eggplant-shaped flask and fully ground for 10 minutes to form a powder (the purpose is to make the metal salt precursor uniformly coated on the template salt crystals, which is to prepare for the subsequent uniform annealing treatment to form an assembly), and then placed in a porcelain boat and wrapped with copper foil for use;

[0062] (2) The porcelain boat was then placed in a high-pressure furnace and heated to 600°C at a heating rate of 10°C / min in a 0.1 MPa argon atmosphere and kept at that temperature for 24 h. The sample was then naturally cooled to room temperature. The sample was taken out of a centrifuge tube and 4 ml of anhydrous ethanol and 4 ml of deionized water were added and ultrasonically cleaned for 5 min. The sample was centrifuged at 8000 r / s for 3 min. The cleaning was repeated 3 times to obtain a black product. The sample was dried at room temperature to obtain a sample.

[0063] Figure 1The low-magnification transmission electron microscopy image of the small-sized and high-loading PtNi alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is an assembly of nanoparticles in-situ anchored by a carbon support, making the whole catalyst a two-dimensional nanoparticle assembly, indicating that its high-loading feature greatly improves the utilization rate of Pt metal and endows the catalyst with higher effective catalytic performance in applications;

[0064] Figure 2 The high-magnification transmission electron microscopy image of the small-sized and high-loading PtNi alloy catalyst is shown, showing that the whole catalyst is assembled by uniformly sized nanoparticles, and combined with Figure 3 the particle size statistical chart shown, the average particle size of the nanoparticles is 3.20 nm, featuring small size, which endows the catalyst with a larger electrochemically active surface area, greatly exposes the active sites, and is conducive to improving its activity;

[0065] Figure 4 The HRTEM image of the small-sized and high-loading PtNi alloy catalyst is shown, showing that individual nanoparticles have ordered lattice fringes, indicating that the catalyst is composed of ordered alloy nanoparticles and has the characteristics of ordered alloys, making the nanoparticles have more stable structural retention and enhancing the stability of the catalyst;

[0066] Figure 5 The XRD pattern of the small-sized and high-loading PtNi alloy catalyst is shown. Its main peak coincides with the standard XRD card of PtNi alloy, and there are superlattice peaks near 25° and 33°, proving that this preparation method successfully synthesizes ordered PtNi alloy, further demonstrating the feasibility and universality of this method.

[0067] Figure 6 The thermogravimetric analysis diagram of the small-sized and high-loading PtNi alloy catalyst is shown. By subjecting the sample to a certain temperature program control at high temperature and observing the change process of the sample mass with temperature or time, it is found that between 0 °C and 350 °C, as the temperature rises, the carbon support is gradually oxidized and decomposed, thus obtaining the remaining metal; after conversion, the loading is 89.9075%, thereby proving that the ordered PtNi alloy catalyst synthesized by this method has a very high metal loading;

[0068] Figure 7 From the element mapping diagram of the small-sized and high-loading PtNi alloy catalyst, it can be found that Pt, Ni, and C elements are all evenly distributed therein, proving that the PtNi alloy catalyst has been successfully synthesized by the method combining high temperature and pressure, and the PtNi nanoparticles have been successfully and functionally anchored on the carbon support, which is also one of the reasons for the excellent stability of the catalyst;

[0069] Figure 8The polarization curves of small-sized, high-loading PtNi alloy catalysts and commercial Pt / C are shown. The figure respectively presents the polarization curves of ordered PtNi alloy catalysts and 60% commercial Pt / C before and after 10,000 cycles of accelerated degradation tests. The electrochemical experiments were all carried out on a CHI 760E electrochemical workstation (Shanghai Chenhua). The experiments used a conventional three-electrode system and were conducted at room temperature. A glassy carbon electrode (GCE, diameter 5 mm, 0.196 cm 2 ) was used as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. The kinetic current was calculated through the limiting diffusion current and the current corresponding to 0.9 V, and the mass activity could be obtained from this. The mass activity of the PtNi alloy catalyst was 0.42 A / mg Pt -1 , and that of 60% commercial Pt / C was 0.16 A / mg Pt -1 ; moreover, by calculating the half-wave potential loss before and after the accelerated degradation test (as shown in the figure), it can be obtained that the PtNi alloy catalyst has good stability compared to commercial Pt / C.

[0070] Example 2

[0071] A preparation method for a small-sized, high-loading PtCo alloy electrocatalyst is as follows:

[0072] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (6.7 mg) of cobalt acetylacetonate, and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve them by ultrasonic treatment for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0073] (2) Then place the porcelain boat into a high-pressure furnace, under a nitrogen atmosphere of 0.5 MPa, with a heating rate of 10 °C / min, heat up to 650 °C and hold for 5 h, and then naturally cool to room temperature. Take out the sample and put it into a centrifuge tube, add 4 ml of anhydrous ethanol and 4 ml of deionized water respectively, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product. Air-dry at room temperature to obtain the sample. The average size of the obtained nanoparticles is 4.11 nm. After calculation, the metal loading of the catalyst is 80.7619%.

[0074] Figure 9The low-magnification transmission electron microscopy image of the small-sized and high-loading PtCo alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is composed of nanoparticles in-situ anchored on the carbon support, making the whole catalyst a nanoparticle assembly with two-dimensional characteristics, indicating that its high-loading feature greatly improves the utilization rate of Pt metal and enables the catalyst to have higher effective catalytic performance in applications;

[0075] Figure 10 The XRD pattern of the small-sized and high-loading PtCo alloy catalyst is shown. Its main peak coincides with the standard XRD card of PtCo alloy, and there are peaks of superlattice near 24° and 33°, which proves that the ordered PtCo alloy is successfully synthesized by this preparation method, demonstrating the feasibility and universality of this method.

[0076] Example 3

[0077] A preparation method for a small-sized and high-loading PtFe alloy electrocatalyst is as follows:

[0078] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (9.0 mg) of iron acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve them by ultrasonic treatment for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into powder (the purpose is to uniformly coat the metal salt precursor on the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), and put it into a porcelain boat and wrap it with copper foil for standby;

[0079] (2) Then put the porcelain boat into a high-pressure furnace, heat it up to 650 °C at a heating rate of 10 °C / min in a nitrogen atmosphere of 0.5 MPa, keep it warm for 1 h, and then naturally cool it to room temperature. Take out the sample and put it into a centrifuge tube, add 4 ml of anhydrous ethanol and 4 ml of deionized water respectively, ultrasonic clean it for 5 min, centrifuge it at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product. Dry it at room temperature to obtain the sample. The average size of the obtained nanoparticles is 4.61 nm. After calculation, the metal loading of the catalyst is 82.44618%.

[0080] Figure 11 The low-magnification transmission electron microscopy image of the small-sized and high-loading PtFe alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is composed of nanoparticles in-situ anchored on the carbon support, making the whole catalyst a nanoparticle assembly with two-dimensional characteristics, indicating that its high-loading feature greatly improves the utilization rate of Pt metal and enables the catalyst to have higher effective catalytic performance in applications;

[0081] Figure 12The XRD pattern of the small-sized and high-loading PtFe alloy catalyst is shown. Its main peak coincides with the standard XRD card of PtFe alloy, and there are peaks of superlattice near 23° and 32°, which proves that the ordered PtFe alloy has been successfully synthesized by this preparation method, demonstrating the feasibility and universality of this method.

[0082] Example 4

[0083] A preparation method of a small-sized and high-loading Pt 3 Ru 2 alloy electrocatalyst, comprising the following steps:

[0084] (1) Mix 0.0762 mmol (30.0 mg) of platinum acetylacetonate, 0.0508 mmol (20.0 mg) of ruthenium acetylacetonate and 600.0 mg of potassium chloride, add 10 ml of anhydrous ethanol and 10 ml of deionized water to dissolve them by mixing, ultrasonicate for 30 min, after fully mixing and dissolving, dry the liquid using a blast drying oven, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0085] (2) Then place the porcelain boat into a high-pressure furnace, in a nitrogen atmosphere of 10 MPa, with a heating rate of 10 °C / min, heat up to 600 °C and hold for 1 h, then naturally cool to room temperature. Take out the sample and put it into a centrifuge tube, add 4 ml of anhydrous ethanol and 4 ml of deionized water respectively, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0086] Figure 13 The transmission electron microscope image of the small-sized and high-loading Pt 3 Ru 2 alloy catalyst shows that the overall morphology of the catalyst is composed of nanoparticles in-situ anchored on the carbon support, making the whole catalyst a nanoparticle assembly with two-dimensional characteristics, indicating that its high-loading characteristic greatly improves the utilization rate of Pt metal and enables the catalyst to have higher effective catalytic performance in applications;

[0087] Figure 14 The small-sized and high-loading Pt 3 Ru 2 From the particle size statistical chart of the alloy catalyst, the average particle size of the nanoparticles is 2.66 nm, with the characteristic of small size, which greatly improves the exposure of active sites by increasing the utilization rate of Pt atoms and is conducive to improving its activity;

[0088] Figure 15 The small-sized and high-loading Pt3 Ru 2 XRD pattern of the alloy catalyst, Pt 3 Ru 2 exhibits a typical fcc structure, and no diffraction peaks of hexagonal close-packed Ru and its oxides are observed, indicating that there is no phase separation, which further proves the formation of the PtRu alloy structure. It is proved that this preparation method successfully synthesizes the pure-phase PtRu alloy, further demonstrating the feasibility and universality of this method.

[0089] Figure 16 Shown are small-sized, high-loading Pt 3 Ru 2 From the elemental mapping diagram of the alloy catalyst, it can be found that Pt, Ru, and C elements are all evenly distributed therein, proving that the Pt 3 Ru 2 alloy catalyst was successfully synthesized by the method combining high temperature and pressure, and the Pt 3 Ru 2 nanoparticles were successfully anchored on the carbon support, which is also one of the reasons for the excellent stability of the catalyst.

[0090] Example 5

[0091] A preparation method of a small-sized, high-loading RuCo alloy electrocatalyst, comprising the following steps:

[0092] (1) Mix 0.0508 mmol of ruthenium acetylacetonate, 0.0508 mmol of cobalt acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, ultrasonicate for 30 min, and after fully mixing and dissolving, use a rotary evaporator to dry the liquid. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat and wrap it with copper foil for standby;

[0093] (2) Then place the porcelain boat into a high-pressure furnace, heat it up to 600 °C at a heating rate of 10 °C / min in a nitrogen atmosphere of 10 MPa, keep it warm for 1 h, and then naturally cool it to room temperature. Take out the sample and put it into a centrifuge tube, add 4 ml of absolute ethanol and 4 ml of deionized water respectively, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0094] Figure 17The transmission electron microscopy image of the small-sized and high-loading RuCo alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is composed of nanoparticles in-situ anchored by a carbon support, making the whole catalyst an assembly of nanoparticles with two-dimensional characteristics, indicating that its high-loading feature greatly improves the utilization rate of Ru metal and enables the catalyst to have higher effective catalytic performance in applications.

[0095] Example 6

[0096] A preparation method for a small-sized and high-loading PtZn alloy electrocatalyst is as follows:

[0097] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (6.6 mg) of zinc acetylacetonate, and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by ultrasonic treatment for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0098] (2) Then place the porcelain boat into a high-pressure furnace, heat it to 650 °C at a heating rate of 10 °C / min in an argon atmosphere of 1 MPa, hold for 1 h, and then naturally cool to room temperature. Take out the sample and put it into a centrifuge tube, add 4 ml of absolute ethanol and 4 ml of deionized water respectively, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0099] Figure 18 The transmission electron microscopy image of the small-sized and high-loading PtZn alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is composed of nanoparticles in-situ anchored by a carbon support, making the whole catalyst an assembly of nanoparticles with two-dimensional characteristics, indicating that its high-loading feature greatly improves the utilization rate of Pt metal and enables the catalyst to have higher effective catalytic performance in applications;

[0100] Figure 19 The XRD pattern of the small-sized and high-loading PtZn alloy catalyst is shown. Its main peak coincides with the standard XRD card of the PtZn alloy, and there are peaks of superlattice near 26° and 32°, proving that this preparation method successfully synthesizes the PtZn alloy and demonstrating the feasibility and universality of this method.

[0101] Example 7

[0102] A preparation method for a small-sized and high-loading PtGa 2 alloy electrocatalyst is as follows:

[0103] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0508 mmol (19.8 mg) of gallium acetylacetonate, and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, ultrasonicate for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0104] (2) Then place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 1 MPa, heat it at a heating rate of 10 °C / min to 600 °C and hold for 1 h, then naturally cool to room temperature. Take out the sample and add 4 ml of absolute ethanol and 4 ml of deionized water to the centrifuge tube, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0105] Figure 20 The transmission electron microscopy image of the small-sized, high-loading PtGa 2 alloy catalyst is shown, demonstrating that the overall morphology of the catalyst is nanoparticles in-situ anchored by a carbon support, making the overall catalyst a nanoparticle assembly with two-dimensional characteristics, indicating that its high-loading characteristic greatly improves the utilization rate of Pt metal and enables the catalyst to have higher effective catalytic performance in applications;

[0106] Figure 21 The XRD pattern of the small-sized, high-loading PtGa 2 alloy catalyst is shown. Its main peak is consistent with the standard XRD card of the PtGa 2 alloy, proving that this preparation method successfully synthesizes the PtGa 2 alloy, demonstrating the feasibility and universality of this method.

[0107] Example 8

[0108] A preparation method for a small-sized, high-loading PtCu alloy electrocatalyst is as follows:

[0109] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (6.5 mg) of copper acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min. After fully mixing and dissolving, dry the liquid using a rotary evaporator. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0110] (2) Then place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 1 MPa, with a heating rate of 10 °C / min, heat up to 700 °C and hold for 1 h, then naturally cool to room temperature. Take out the sample and add 4 ml of absolute ethanol and 4 ml of deionized water to a centrifuge tube, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0111] Example 9

[0112] A preparation method for a small-sized and high-loading PtMn alloy electrocatalyst is as follows:

[0113] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0254 mmol (6.6 mg) of manganese acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min. After fully mixing and dissolving, dry the liquid using a rotary evaporator. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0114] (2) Then place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 5 MPa, with a heating rate of 10 °C / min, heat up to 700 °C and hold for 1 h, then naturally cool to room temperature. Take out the sample and add 4 ml of absolute ethanol and 4 ml of deionized water to a centrifuge tube, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0115] Example 10

[0116] A preparation method for a small-sized and high-loading IrNi alloy electrocatalyst is as follows:

[0117] (1) Mix 0.0254 mmol (10.0 mg) of iridium acetylacetonate, 0.0254 mmol (6.7 mg) of nickel acetylacetonate, and 400.0 mg of potassium chloride. Add 5 ml of absolute ethanol and 5 ml of deionized water and dissolve them by mixing. Sonicate for 30 min. After complete dissolution by thorough mixing, dry the liquid using a rotary evaporator. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to form a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly). Place it in a porcelain boat, wrap it with copper foil, and set aside;

[0118] (2) Then place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 50 MPa, with a heating rate of 10 °C / min, heat up to 650 °C and hold for 5 h. Then cool naturally to room temperature. Take out the sample and put it into a centrifuge tube. Add 4 ml of absolute ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the washing 3 times to obtain a black product. Air-dry at room temperature to obtain the sample.

[0119] Example 11

[0120] A preparation method for a small-sized and high-loading RhNi alloy electrocatalyst, the steps are as follows:

[0121] (1) Mix 0.0254 mmol (10.0 mg) of rhodium acetylacetonate, 0.0254 mmol (6.7 mg) of nickel acetylacetonate, and 400.0 mg of potassium chloride. Add 5 ml of absolute ethanol and 5 ml of deionized water and dissolve them by mixing. Sonicate for 30 min. After complete dissolution by thorough mixing, dry the liquid using a rotary evaporator. Then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to form a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly). Place it in a porcelain boat, wrap it with copper foil, and set aside;

[0122] (2) Then place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 10 MPa, with a heating rate of 10 °C / min, heat up to 1500 °C and hold for 1 h. Then cool naturally to room temperature. Take out the sample and put it into a centrifuge tube. Add 4 ml of absolute ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, and repeat the washing 3 times to obtain a black product. Air-dry at room temperature to obtain the sample.

[0123] Example 12

[0124] A preparation method for a small-sized and high-loading PdNi alloy electrocatalyst, the steps are as follows:

[0125] (1) Mix 0.0254 mmol (8.9 mg) of palladium acetylacetonate, 0.0254 mmol (6.7 mg) of nickel acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min, after fully mixing and dissolving, dry the liquid using a rotary evaporator, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), place it in a porcelain boat and wrap it with copper foil for standby;

[0126] (2) Then place the porcelain boat into a high-pressure furnace, in an argon atmosphere of 3 MPa, with a heating rate of 10 °C / min, heat up to 500 °C and hold for 2 h, then naturally cool to room temperature, take out the sample into a centrifuge tube, add 4 ml of absolute ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0127] Example 13

[0128] A preparation method of a small-size and high-loading PtNiCo alloy electrocatalyst, the steps are as follows:

[0129] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0127 mmol (3.3 mg) of nickel acetylacetonate, 0.0127 mmol (3.3 mg) of cobalt acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min, after fully mixing and dissolving, dry the liquid using a rotary evaporator, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), place it in a porcelain boat and wrap it with copper foil for standby;

[0130] (2) Then place the porcelain boat into a high-pressure furnace, in an argon atmosphere of 5 MPa, with a heating rate of 10 °C / min, heat up to 800 °C and hold for 12 h, then naturally cool to room temperature, take out the sample into a centrifuge tube, add 4 ml of absolute ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0131] Example 14

[0132] A preparation method of a small-size and high-loading PtRuCo alloy electrocatalyst, the steps are as follows:

[0133] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0127 mmol (5.0 mg) of ruthenium acetylacetonate, 0.0127 mmol (3.3 mg) of cobalt acetylacetonate, and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min, after fully mixing and dissolving, dry the liquid using a rotary evaporator, then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0134] (2) Then place the porcelain boat into a high-pressure furnace, in an argon atmosphere of 10 MPa, with a heating rate of 10 °C / min, heat up to 750 °C and hold for 3 h, then naturally cool to room temperature, take out the sample and put it into a centrifuge tube, add 4 ml of anhydrous ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the washing 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0135] Example 15

[0136] A preparation method for a small-sized and high-loading PtNiCoFe alloy electrocatalyst is as follows:

[0137] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0085 mmol (2.3 mg) of nickel acetylacetonate, 0.0085 mmol (2.2 mg) of cobalt acetylacetonate, 0.0085 mmol (3.0 mg) of iron acetylacetonate, and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve them by mixing, sonicate for 30 min, after fully mixing and dissolving, dry the liquid using a rotary evaporator, then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystals, which prepares for the subsequent uniform annealing treatment to form an assembly), and place it in a porcelain boat wrapped with copper foil for standby;

[0138] (2) Then place the porcelain boat into a high-pressure furnace, in an argon atmosphere of 7 MPa, with a heating rate of 10 °C / min, heat up to 700 °C and hold for 5 h, then naturally cool to room temperature, take out the sample and put it into a centrifuge tube, add 4 ml of anhydrous ethanol and 4 ml of deionized water respectively, sonicate for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the washing 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0139] Example 16

[0140] Preparation method of a small-sized and high-loading PtNiCoFeZn alloy electrocatalyst, the steps are as follows:

[0141] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0064 mmol (1.7 mg) of nickel acetylacetonate, 0.0064 mmol (1.7 mg) of cobalt acetylacetonate, 0.0064 mmol (2.3 mg) of iron acetylacetonate, 0.0064 mmol (1.7 mg) of zinc acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve by mixing, ultrasonicate for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), put it into a porcelain boat and wrap it with copper foil for standby;

[0142] (2) Then put the porcelain boat into a high-pressure furnace, in a nitrogen atmosphere of 10 MPa, heat it up at a heating rate of 10 °C / min to 650 °C, keep it warm for 5 h, and then naturally cool it to room temperature. Take out the sample and add 4 ml of anhydrous ethanol and 4 ml of deionized water to the centrifuge tube, ultrasonically clean it for 5 min, centrifuge it at a speed of 8000 r / s for 3 min, and repeat the cleaning 3 times to obtain a black product, and dry it at room temperature to obtain the sample.

[0143] Example 17

[0144] Preparation method of a small-sized and high-loading PtNiCoFeCu alloy electrocatalyst, the steps are as follows:

[0145] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0064 mmol (1.7 mg) of nickel acetylacetonate, 0.0064 mmol (1.7 mg) of cobalt acetylacetonate, 0.0064 mmol (2.3 mg) of iron acetylacetonate, 0.0064 mmol (1.7 mg) of copper acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of anhydrous ethanol and 5 ml of deionized water to dissolve by mixing, ultrasonicate for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid, and then scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into a powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), put it into a porcelain boat and wrap it with copper foil for standby;

[0146] (2) Then, place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 10 MPa, heat it at a heating rate of 10 °C / min to 700 °C, hold the temperature for 5 h, and then naturally cool it to room temperature. Take out the sample and add 4 ml of absolute ethanol and 4 ml of deionized water to a centrifuge tube, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and air-dry it at room temperature to obtain the sample.

[0147] Example 18

[0148] A preparation method for a small-sized and high-loading PtNiCoFeZnCu alloy electrocatalyst, the steps are as follows:

[0149] (1) Mix 0.0254 mmol (10.0 mg) of platinum acetylacetonate, 0.0051 mmol (1.4 mg) of nickel acetylacetonate, 0.0051 mmol (1.3 mg) of cobalt acetylacetonate, 0.0051 mmol (1.8 mg) of iron acetylacetonate, 0.0051 mmol (1.3 mg) of zinc acetylacetonate, 0.0051 mmol (1.3 mg) of copper acetylacetonate and 400.0 mg of potassium chloride, add 5 ml of absolute ethanol and 5 ml of deionized water to mix and dissolve, ultrasonically clean for 30 min. After fully mixing and dissolving, use a rotary evaporator to dry the liquid. Then, scrape the solid sample from the eggplant-shaped flask and grind it thoroughly for 10 minutes to make it into powder (the purpose is to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly), place it in a porcelain boat and wrap it with copper foil for standby;

[0150] (2) Then, place the porcelain boat into a high-pressure furnace. Under an argon atmosphere of 1 MPa, heat it at a heating rate of 10 °C / min to 650 °C, hold the temperature for 5 h, and then naturally cool it to room temperature. Take out the sample and add 4 ml of absolute ethanol and 4 ml of deionized water to a centrifuge tube, ultrasonically clean for 5 min, centrifuge at a speed of 8000 r / s for 3 min, repeat the cleaning 3 times to obtain a black product, and air-dry it at room temperature to obtain the sample.

[0151] As can be seen from the above examples, with this salt template method as a reference, the present invention further improves the preparation method by combining pressure-assisted regulation and traditional high-temperature annealing. Thus, under the condition of alloying particles at traditional high temperature, pressure is added to limit the growth of particle size and make it uniform, so that pressure assistance and high-temperature annealing work together to prepare a small-sized and high-loading noble metal alloy electrocatalyst, thereby further reducing its cost and improving the activity and stability of the catalyst.

[0152] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

[0153] Matters not covered by the present invention are well-known techniques.

Claims

1. A small-sized, high-loading noble metal alloy electrocatalyst, characterized in that the electrocatalyst comprises an in-situ carbon support and small-sized noble metal alloy nanoparticles supported on the support; the loading amount is 50 wt% to 90 wt%; the noble metal alloy is an alloy composed of a noble metal and at least one different transition metal M, and the average particle size of the noble metal alloy nanoparticles is 1 to 10 nm; wherein, the noble metal is one of platinum, palladium, iridium, rhodium, ruthenium, and the transition metal M is at least one of iron, cobalt, nickel, copper, manganese, zinc, gallium, platinum, palladium, iridium, rhodium, ruthenium.

2. The preparation method of the small-sized, high-loading noble metal alloy electrocatalyst according to claim 1, characterized in that the preparation method comprises the following steps: Step 1, adding an organic noble metal salt precursor, a transition metal M metal salt precursor, and a template salt into a mixed solvent for mixing, ultrasonic stirring for 20 to 40 minutes, drying and grinding, and obtaining a powder sample for standby; wherein, the mixed solvent composition is anhydrous ethanol / deionized water; 0.01 mmol to 0.05 mmol of the organic noble metal salt precursor, 0.01 mmol to 0.05 mmol of the transition metal M metal salt precursor, and 50 mg to 1000 mg of the template salt are added to every 10 mL of the mixed solvent; the mass ratio of the organic noble metal salt precursor to the template salt is 1:5 to 1:100; the molar ratio of the organic noble metal salt precursor to the transition metal M metal salt precursor is 10:1 to 1:10; Step 2, transferring the above powder sample into a high-pressure furnace, heating to 500 °C to 1500 °C, annealing in an inert atmosphere for 0.5 h to 48 h, after cooling to room temperature, washing several times with an anhydrous ethanol / deionized water mixed solution, centrifuging to collect the black product, and drying to obtain different kinds of small-sized, high-loading noble metal alloy catalysts; the pressure of the inert atmosphere is 0.1 MPa to 50 MPa higher than the standard atmospheric pressure; the organic noble metal salt precursor is platinum acetylacetonate, palladium acetylacetonate, iridium acetylacetonate, rhodium acetylacetonate, or ruthenium acetylacetonate; the transition metal M metal salt precursor is at least one of iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate, manganese acetylacetonate, zinc acetylacetonate, gallium acetylacetonate, platinum acetylacetonate, palladium acetylacetonate, iridium acetylacetonate, rhodium acetylacetonate, ruthenium acetylacetonate; the template salt is one of potassium chloride, potassium bromide, sodium chloride, sodium bromide, sodium carbonate, sodium acetate.

3. The preparation method of the small-sized, high-loading noble metal alloy electrocatalyst according to claim 2, characterized in that the volume ratio of anhydrous ethanol / deionized water in the mixed solvent is 1:

1.

4. The preparation method of the small-sized, high-loading noble metal alloy electrocatalyst according to claim 2, characterized in that the drying method of the mixed solution in Step 1 is rotary evaporation solvent drying method or blast oven drying method, and after drying, the solid powder is fully ground for 5 to 10 minutes, aiming to uniformly coat the metal salt precursor onto the template salt crystal, which prepares for the subsequent uniform annealing treatment to form an assembly.

5. The preparation method of the small-sized and high-loading noble metal alloy electrocatalyst according to claim 2, characterized in that the heat treatment annealing temperature is 500°C to 1500°C, the pressure of the inert atmosphere for heat treatment is 0.1 MPa to 50 MPa higher than the standard atmospheric pressure, and the inert atmosphere is one of argon and nitrogen, the purpose is to make the metal particles more evenly dispersed during calcination, the heating rate is 1°C / min to 50°C / min, and the heat preservation time is 1 h to 24 h.

6. The preparation method of the small-sized and high-loading noble metal alloy electrocatalyst according to claim 2, characterized in that in the above step two, the volume ratio of the cleaning liquid anhydrous ethanol / deionized water is 3:1 to 1:3, and the number of cleaning times is 1 to 5 times.

7. The application of the small-sized and high-loading noble metal alloy electrocatalyst according to claim 1 can be used in but not limited to proton exchange membrane fuel cells as the electrocatalyst of the membrane electrode.

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